1. Field of the Invention
This invention relates to magnetic recording mediums in the form of tapes or disks.
2. Description of the Prior Art
In recent years, the technical advancement in the field of magnetic recording and reproducing apparatus, such as domestic video tape recorders, is remarkable. High density recording is now being attained as a result of the technical advancement.
However, the high density recording is not only brought about by the progress in magnetic recording and reproducing apparatus, but has to be accompanied by an improvement in magnetic recording mediums corresponding to the technical progress of the apparatus.
In this view, it is believed that non-magnetic base films should have surfaces which are as smooth as possible. However, magnetic recording medium, which have a magnetic recording layer formed on smooth base films, have the problem of durability, such as a poor resistance to wear, along with the drawback of a poor travelling performance.
In order to solve the problems, there have been proposed magnetic recording mediums which have a back coat layer on one side of a base film opposite to a side on which a magnetic recording layer is formed (Japanese Laid-open Patent Application Nos. 59-5423, 59-5429 and 59-5430). However, these mediums do not have a satisfactory durability and undesirably tend to be electrically charged.
Moreover, there has also been proposed a magnetic recording medium having a back coat layer which is made of a composition comprising carbon black and lubricants dispersed in a binder. However, this medium is disadvantageous in that the carbon lack particles in the back coat layer are liable to come off when the medium is wound about reels. The resultant dust is transferred to the surface of the magnetic recording layer, causing dropout defects to occur and the travelling performance to lower.